Methods and apparatuses for automatically bringing a lens into a focussing position with respect to an image in a field of view are well-known in the art. In the prior art, such methods and apparatuses have employed sonar or infrared transmission and reception to determine the distance of the lens to the image and determining the best focal position therefrom. All of these techniques are termed active distance determination techniques. The disadvantage of an active distance determination technique is that energy must be expended in generating the sonar or the infrared signal. In consumer electronics or in portable cameras, the use of an active distance determination technique shortens the battery life. Further, the techniques necessarily include circuitry for both transmission and detection of the medium.